Organic polyfunctional epoxy monomers are useful compounds that can be widely used in various industrial fields including the chemical industry as raw materials of resist materials (and particularly solder resist materials), and as intermediates of agricultural chemicals and pharmaceuticals as well as raw materials of various polymers such as plasticizers, adhesives or coating resins.
However, technology for selectively epoxidating only one double bond at a specific position in a diolefin has low productivity (low reactivity, low selectivity), and the technical scope of that technology is frequently limited to only certain types of structures.
Although peracids have conventionally been used as selective epoxidation agents for diolefins (see, for example, Chem. Ber., 1985, 118, 1267-1270), this technique has problems such as the formation of large amounts of diepoxides as by-products and corrosion of equipment due to the equivalent formation of acid derived from an oxidizing agent.
Although a process for selectively epoxidating diolefins is also known that uses oxone as an oxidizing agent in the presence of a ketone catalyst (see, for example, J. Org. Chem., 1998, 63, 2948-2953), in this reaction, in addition to requiring a considerably large amount of the ketone catalyst (20 to 30 mol % based on the diolefin), there is also the problem of the need to rigorously control reaction conditions such as the pH of the reaction solution and reaction temperature in order to inhibit decomposition of oxone during the reaction.
On the other hand, hydrogen peroxide is an oxidizing agent that is excellent for industrial use since it is inexpensive, does not cause corrosion, and places little burden on the environment since it does not form any by-products after reacting or only forms water.
Examples of conventional known processes for producing epoxy compounds from olefins using hydrogen peroxide as an epoxidation agent include: (1) an epoxidation process that uses hydrogen peroxide in the presence of quaternary ammonium chloride, phosphoric acid and a tungsten metal salt (see Japanese Unexamined Patent Publication No. 2003-192679 (hereinafter referred to as Patent Document 1) and Japanese Unexamined Patent Publication No. 2004-115455 (hereinafter referred to as Patent Document 2)), (2) an epoxidation process that uses a phase transfer catalyst in the manner of a quaternary ammonium salt and uses a tungstic acid and an α-aminomethylphosphonic acid as catalysts in an organic solvent (see Japanese Unexamined Patent Publication No. H8-27136 (hereinafter referred to as Patent Document 3)), (3) an epoxidation process carried out in the presence of a tungsten oxide obtained by reacting a tungsten compound and hydrogen peroxide, quaternary ammonium hydrogen sulfate and phosphoric acid in a toluene solvent (see Japanese Unexamined Patent Publication No. 2004-59573 (hereinafter referred to as Patent Document 4)), (4) an epoxidation process that uses a multi-component oxidation catalyst comprising a tungsten compound, quaternary ammonium salt, phosphoric acid and/or boric acid and hydrogen sulfate in the presence of an organic solvent such as toluene (see Japanese Unexamined Patent Publication No. 2005-169363 (hereinafter referred to as Patent Document 5), and (5) an epoxidation process carried out in a chloroform solvent using a catalyst having both phase transfer ability and epoxidation ability such as a cetylpyridinium salt of a heteropolyacid (see J. Org. Chem., 1988, 53, 3587-3593 (hereinafter referred to as Non-Patent Document 1)). However, since all of these processes use an organic solvent and a quaternary ammonium salt having both phase transfer ability and high surface activation ability, reaction efficiency as well as ease of separation of the organic layer and aqueous layer following reaction are not satisfactory.
In addition, although a reaction system has also been reported in which a reaction is carried out without using an organic solvent (see Japanese Unexamined Patent Publication No. 2006-316034 (hereinafter referred to as Patent Document 6)), in this system as well, since it is necessary to use a catalyst having strong phase transfer ability in the manner of a quaternary ammonium salt, and since the phase transfer catalyst has surface activity, phase separation following completion of the reaction is not easy.
In addition, not only is phase separation not easy, but when a quaternary ammonium salt is mixed into the organic layer an attempted to be used, it has serious detrimental effects on electrical properties and the like, and in the case of carrying out distillation or other purification, the quaternary ammonium salt is decomposed by heat, thereby resulting in problems such as poor distillation yield.
Known examples of processes that use a catalyst other than tungsten include: (6) an epoxidation process that uses hydrogen peroxide and a catalyst in which methyl trioxolenium (CH3ReO3) and a strong organic base compound are loaded on an inorganic oxide support (see Japanese Unexamined Patent Publication No. 2001-25665 (hereinafter referred to as Patent Document 7)), (7) an epoxidation process that uses hydrogen peroxide in the presence of a titanium-containing zeolite catalyst and an additive containing a tertiary amine, tertiary amine oxide or mixture thereof (see Japanese Unexamined International Patent Publication No. 2002-526483 (hereinafter referred to as Patent Document 8), and (8) an epoxidation process that uses hydrogen peroxide in the presence of a fluoroalkylketone (see Chem. Commun., 1999, 263-264 (hereinafter referred to as Non-Patent Document 2)). However, these processes have poor catalytic efficiency, require an excess of hydrogen peroxide, or are subject to restrictions such as only being able to be applied to small substrates.